JP5081677B2 - Copper tube for cross fin tube type heat exchanger - Google Patents

Description

  The present invention relates to a copper tube used in a cross fin tube heat exchanger.

  Conventionally, a heat exchanger of a refrigerator such as an air conditioner such as a room air conditioner, a refrigerator, or a freezer is configured by a cross fin tube configured by combining a number of fins and a heat transfer tube (see Patent Document 1). . As the heat transfer tube, a copper tube (hereinafter referred to as a copper tube) made of copper and a copper alloy having excellent heat transfer properties, workability, and corrosion resistance is used. Moreover, the said fin processes the cylindrical collar part for inserting and fixing the said heat exchanger tube to the fin material for heat exchangers which consist of an aluminum plate.

  When manufacturing a heat exchanger, a large number of the fins are stacked, the copper tube is inserted into a cylindrical collar portion provided on the fin, and the copper tube is expanded, whereby the copper tube and the fin are combined. Assemble as one.

The copper pipe can be obtained by unwinding the level wound coil and then cutting and bending it to a predetermined length.
The level-wound coil is generally provided with lubricating oil on the inner and outer surfaces of a copper tube, subjected to a drawing process so as to have a predetermined size and inner surface shape, and a copper tube of several thousand meters is aligned and wound. It is formed by performing an annealing process so as to have a predetermined tempering.

  In addition, as described above, the copper pipe is obtained by unwinding the level wound coil and then cutting and bending it to a predetermined length. There has been a problem that the surface quality of the copper pipe deteriorates due to adhesion between each other and friction between the copper pipes when unrolling, and scratches generated on the pipe surface. From the viewpoint of quality improvement and yield improvement, there is a strong demand for the copper tube surface to be free from burn-in scratches and the like.

  Further, when the copper tube is inserted into the fin, if the surface of the copper tube is not slippery, the copper tube is caught and the fin is deformed or the copper tube is bent.

JP-A-9-329398

  This invention is made | formed in view of this conventional problem, Comprising: It aims at providing the copper pipe for cross fin tube type heat exchangers which has the outstanding surface quality and was excellent in the insertability.

In the present invention, the copper tube and the fin are integrally assembled by inserting and arranging a copper tube made of copper or a copper alloy in a cylindrical collar portion provided on a fin made of aluminum or an aluminum alloy. A copper tube for a cross fin tube type heat exchanger composed of a cross fin tube,
In the Auger electron spectroscopic analysis method (hereinafter referred to as AES analysis method), the surface of the copper tube has a thickness at which the carbon amount is halved with respect to the carbon amount on the outermost surface of the copper tube. A film made of a carbon compound having a thickness of 1.0 to 500 nm is formed ,
The coating is formed on a copper tube for a cross-fin tube heat exchanger , wherein the coating is formed by applying a lubricating oil to the copper tube and then performing an annealing treatment in a non-oxidizing atmosphere. 1).

  The most notable point of the copper pipe for a cross fin tube type heat exchanger of the present invention is that the depth of the carbon amount is halved with respect to the carbon amount on the outermost surface of the copper tube on the surface in the AES analysis method. In the case of a thickness, the film has a film made of a carbon compound having a film thickness of 1.0 to 500 nm.

  In the AES analysis method, a cross fin tube having excellent surface quality and excellent insertability is produced by forming a film made of a carbon compound having a film thickness of 1.0 to 500 nm after annealing. A copper tube for a mold heat exchanger can be obtained. And the improvement of productivity and quality of a cross fin tube can be aimed at by the improvement of insertability.

  As described above, the copper tube for the cross fin tube type heat exchanger of the present invention has a film thickness on the surface at which the carbon amount is halved with respect to the carbon amount on the outermost surface of the copper tube in the AES analysis method. The film is made of a carbon compound having a thickness of 1.0 to 500 nm.

  When the film thickness is less than 1.0 nm, discoloration may occur on the surface of the copper tube, or it may be difficult to improve the insertability when the copper tube is inserted into an aluminum fin. On the other hand, when the film thickness exceeds 500 nm, there is a problem that discoloration occurs on the surface of the copper tube and an excellent surface quality cannot be obtained, and there are problems such as poor brazing during assembly of the heat exchanger.

  The AES analysis method is a method in which an electron beam is irradiated onto a solid surface, an electron energy distribution emitted by Auger transition is measured, and an element on the sample surface (depth several nm) is identified and quantified. Since an electron beam as an excitation source can be finely focused, it is excellent in analyzing a minute region, and since it can be scanned, two-dimensional information can be easily obtained.

In addition, as a method for producing a copper tube for a cross fin tube type heat exchanger so that the film is formed, a lubricating oil is applied to the inner surface and the outer surface of the copper tube so as to obtain a predetermined size and inner shape. Applying the lubricant to the surface of the copper tube by adjusting the coating amount, aligning and winding up the copper tube of several thousand meters to produce a level wound coil, and then achieving a predetermined tempering There is a method in which an annealing treatment is performed in a non-oxidizing atmosphere, and then the level wound coil is uncoiled, cut, and bent. And the said film | membrane can be adjusted with the application quantity of the lubricating oil performed before alignment winding, and the optimal quantity can be calculated | required by experiment for every kind of oil.
Various types of lubricating oil can be used. For example, there are ester type and mineral oil type.

  The film made of the carbon compound is preferably formed on the entire surface of the copper tube, but may not necessarily be present on the entire surface of the copper tube, and the above-described effects can be sufficiently obtained. There may be an exposed portion of copper as far as possible.

Moreover, it is preferable that the surface roughness of the said copper pipe in the pipe-axis direction of the said copper pipe is 0.1-2.0 micrometers in Ra (Claim 2).
In this case, in particular, the surface of the copper tube can be made low friction, and the insertability of the copper tube can be further improved.

  The surface roughness of the copper pipe in the axial direction is affected by the drawing die roughness and drawing speed in the drawing process at the time of producing the copper pipe, and the alignment winding and annealing treatment, level coil coil uncoiling and cutting. And little change before and after bending. Therefore, the surface roughness can be adjusted according to the conditions of the drawing die roughness and drawing speed in the drawing process.

  When the surface roughness Ra is less than 0.1 μm, the production efficiency may be deteriorated due to the reduction of the drawing speed, or the drawing die surface polishing cost may be increased in order to reduce the roughness. On the other hand, when the surface roughness exceeds 2.0 μm in Ra, the friction between the copper tube and the collar portion increases when the copper tube is inserted into the collar portion provided on the fin, Insertability may be reduced.

  In addition, the copper pipe is uncoiled by ETS method (Eye to the Sky) in which the copper pipe is pulled out from the inner surface side of the level wound coil arranged with the coil axis vertical, cut and bent. It is preferable to produce by applying (Claim 3).

The ETS method is a level-wound coil unwinding (uncoiling) method that is employed to simplify the unwinding process from the viewpoint of improving production efficiency and yield.
In the ETS system, a copper tube is drawn from the inner surface side of the level-wound coil, and the level-wound coil is unwound from the inner surface side. Therefore, the efficiency is greatly improved as compared with the conventional uncoil method, and no special equipment is required, so that the yield can be improved.

  The level-wound coil is formed by aligning and winding the drawn copper pipe as described above, and then performing an annealing process so as to obtain a predetermined tempering. If the copper tubes adhere to each other during the annealing treatment, there is a problem that the surface of the tube is scratched due to friction between the copper tubes.

  Then, the copper pipe for cross fin tube type heat exchangers of this invention is produced so that it may have excellent surface quality and form a film that imparts insertability to the copper pipe. In this case, the film is formed so as to be formed after annealing, and there is no adhesion between copper tubes or discoloration of the copper tube surface during annealing. Therefore, it is possible to obtain the copper pipe for a cross fin tube type heat exchanger with improved productivity and improved yield.

Example 1
In this example, an example and a comparative example according to the copper tube for a cross fin tube type heat exchanger of the present invention will be described.
This will be described in detail below.

  First, the copper dephosphorized pipe having a total weight of 500 kg is subjected to a rolling process so that the outer diameter of the copper pipe is 7.00 mm, the inner diameter of the copper pipe is 6.35 mm, the thickness is 0.25 mm, and the length is about 5000 m. A level-wound coil weighing 250 kg was produced.

In the above rolling process, the cross-sectional shape having a large number of ripple fins protruding inward was formed by performing the process under the conditions of a fin height of 0.24 mm, a fin apex angle of 10 °, and a lead angle of 30 °.
In addition, the surface roughness of the copper tube after the rolling process was adjusted by changing the degree of polishing of the surface of the rolling die.

In the above-described aligned winding, lubricating oil (polyethylene glycol-polypropylene glycol-polyethylene glycol block polymer (average molecular weight 2220, EO 10%)) was applied to the surface of the copper tube. Thereafter, annealing was performed in an inert gas at 520 ° C. for 1 hour.
Moreover, as shown in Table 1, the application amount of the lubricating oil was changed from 0.1 to 1800 mg / m ² .

  Next, the obtained level wound coil was unwound by the ETS method. The level-wound coil was unwound by arranging it with the coil axis vertical and pulling out the copper tube while unwinding the coil from the inner surface side of the level-wound coil. Then, it cut | disconnected to predetermined length and gave the bending process, and produced the copper pipe (sample E1-sample E5, sample C1, and sample C2) for cross fin tube type heat exchangers.

<AES analysis method>
Next, Auger electron spectroscopy analysis (hereinafter referred to as AES analysis) was performed on the obtained copper tubes for the cross fin tube type heat exchanger (samples E1 to E5, sample C1 and sample C2).
The AES analysis method was performed using a Model 680 Auger Electron Spectroscopy (hereinafter referred to as AES) manufactured by ULVAC-PHI.
Measurement was performed at an acceleration voltage of 10 kV and a sample current of 10 nA.
Ar ion sputtering is performed at an acceleration voltage of 3 kV, and the sputtering speed at that time is 10.5 １ / min (in terms of SiO ₂ ).
The film thickness was measured by setting the depth at which the carbon content is halved relative to the carbon content at the outermost surface of the copper tube as the film thickness. The results are shown in Table 1.

  As is known from Table 1, Sample E1 to Sample E5 have an above-mentioned film thickness of 1 to 500 nm and are examples of the present invention. Sample C1 and Sample C2 are comparative examples of the present invention because the film thickness is out of the scope of the present invention.

  Next, surface roughness Ra was measured about the said sample E1-sample E5, the sample C1, and the sample C2, and copper pipe insertion property and the copper pipe outer surface were evaluated. The results are shown in Table 1.

<Surface roughness Ra>
The surface roughness Ra was measured according to JIS B0601.

<Copper tube insertability>
Overlap 600 aluminum fins with insertion holes, drop a 350 mm long copper tube vertically toward the insertion hole, and observe whether the copper tube is caught when inserting the copper tube, Copper tube insertion was evaluated. The case where the copper tube was not caught was regarded as acceptable (evaluation ○), and the case where the copper tube was caught was regarded as unacceptable (evaluation x).

<Copper tube outer surface>
Ten samples having a length of 300 mm were taken from an arbitrary position from the unwound copper tube, and the surface was visually observed to evaluate the surface of the copper tube. The case where evaluation is (circle) is a pass, and the case where evaluation is x is disqualified.

(Evaluation criteria)
○: When clear flaws and discoloration are not recognized.
X: When a clear crack and discoloration are recognized.

As is known from Table 1, Sample E1 to Sample E5 as examples of the present invention showed good results in all items.
Therefore, according to the present invention, a copper pipe for a cross fin tube type heat exchanger having excellent surface quality and excellent insertability can be obtained.

  Further, as is known from Table 1, the sample C1 as a comparative example of the present invention has a depth of halving the carbon amount on the outermost surface of the copper tube below the lower limit of the present invention. In addition, adhesion due to diffusion bonding between copper tubes during annealing and surface scratches due to friction between copper tubes during uncoiling occurred, and the copper tube outer surface evaluation was rejected.

  In addition, the sample C2 as a comparative example of the present invention has the reason that the depth at which the carbon amount is halved with respect to the carbon amount on the outermost surface of the copper tube exceeds the upper limit of the present invention, so that the discoloration of the copper tube surface occurs. Therefore, the copper tube outer surface evaluation was unacceptable.

(Example 2)
In this example, as shown in FIG. 1, the copper tube 1 and the copper tube 1 for the cross fin tube type heat exchanger are inserted into the cylindrical collar portion provided on the fin 2 made of aluminum. The heat exchanger 3 is a cross fin tube in which the fins 2 are integrally assembled.

In producing the heat exchanger 3, specifically, first, a cylindrical collar portion was press-molded into an aluminum fin material for a heat exchanger to form a fin 2. Then, the copper tube 1 was inserted into a cylindrical collar portion provided on the fin 2. Next, the copper tube 1 was expanded, and the fin 2 and the copper tube 1 were fixed to produce a cross fin tube type heat exchanger 3.
As the copper tube 1 for the cross fin tube type heat exchanger, the sample E1 of Example 1 was used.
As the aluminum fin material for heat exchanger, a surface-treated aluminum material CC509 (plate thickness: 100 μm) manufactured by Sumitomo Light Metal Industry Co., Ltd. was used.

  As described above, since the copper tube 1 of the present invention is adopted as the copper tube, the characteristic that the insertability into the fin 2 is good is fully utilized, and problems such as deformation of the fin and bending of the copper tube 1 occur. The cross fin tube type heat exchanger 3 could be easily obtained without the occurrence of.

Explanatory drawing which shows the cross fin tube type heat exchanger in Example 2. FIG.

Explanation of symbols

1 Copper tube for cross fin tube type heat exchanger 2 Fin 3 Cross fin tube type heat exchanger

Claims (3)

A cross fin tube in which the copper tube and the fin are integrally assembled by inserting and arranging a copper tube made of copper or a copper alloy in a cylindrical collar portion provided on a fin made of aluminum or an aluminum alloy. A copper tube for a cross fin tube type heat exchanger comprising:
In the Auger electron spectroscopic analysis method (hereinafter referred to as AES analysis method), the surface of the copper tube has a thickness at which the carbon amount is halved with respect to the carbon amount on the outermost surface of the copper tube. A film made of a carbon compound having a thickness of 1.0 to 500 nm is formed ,
The coating is formed by applying a lubricating oil to the copper pipe and then subjecting the copper pipe to an annealing treatment in a non-oxidizing atmosphere .   The copper tube for a cross fin tube type heat exchanger according to claim 1, wherein the surface roughness of the copper tube in the tube axis direction is 0.1 to 2.0 µm in Ra. 3. The copper pipe according to claim 1, wherein the copper pipe is uncoiled by an ETS method in which the copper pipe is pulled out from the inner surface side of the level wound coil arranged with the coil axis vertical and cut and bent. The copper pipe for cross fin tube type heat exchangers manufactured by being manufactured.

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